1. Field of Invention
Embodiments disclosed herein relate generally to equipment for use in oil field applications. In particular, embodiments disclosed herein relate to tensioner systems for tensioning of marine risers.
2. Related Technology
Risers are used for offshore oil and gas wells to connect the subsea wellhead to the topside equipment on a floating production platform. Typically, a riser system is employed to provide a conduit from a floating vessel at the water surface where the blowout preventer (BOP) stack or production tree are located down to the wellhead at the sea floor.
Tensioners are employed at the platform to apply tension to the risers. A tensioning system maintains a variable tension to the riser string, thereby alleviating the potential for compression, which can lead to buckling or failure of the risers. Another purpose of a tensioner is to serve as a motion compensator. A tensioner that is incorporated into a riser string can compensate for vessel motion induced by wave action and heave.
A typical tensioner comprises a set of hydraulic cylinders with telescoping piston and cylinder arrangements supplied with gas pressure from external or integral accumulator chambers. Vessel motion relative to a fixed point, possibly due to waves or currents, causes the piston and cylinder to extend and retract.